You can’t actually play any games in the app, nor can you purchase them. For now, you can only spectate other games, send messages to friends, browse OnLive’s library and watch trailers for upcoming titles.

Of course, watching someone else play a video game is kind of like being at a rock concert without hearing the music*. OnLive does plan to have playable games on the iPad, but it’s not clear which ones will get the touch screen treatment.

Even bigger plans await: According to VentureBeat, OnLive also plans to stream Windows 7 apps to iOS devices. While virtual computing has been possible for a while on the iPad with apps like iTeleport and LogMeIn Ignition, OnLive presumably wouldn’t require you to host Windows apps on another computer. As with games, OnLive could stream apps its own servers.

That’s where I start to wonder if Apple’s going to let it happen. Essentially, OnLive would be setting up its own apps and games marketplace within iOS, and it could become robust enough to undermine Apple’s own ecosystem. Not surprisingly, OnLive is also working on an Android app, which runs no risk of being yanked. Whatever happens, it’ll be interesting to watch.

*One exception: Hand-to-hand fighting games like Street Fighter can seem like choreographed movie fight scenes when the players are skilled enough, but OnLive doesn’t have any games from this genre.